debugger: make requestMark() more robust for editors not representing files

src/plugins/debugger/debuggerengine.cpp

@@ -1193,6 +1193,7 @@ void DebuggerEnginePrivate::doInterruptInferior()
 
 void DebuggerEnginePrivate::doShutdownInferior()
 {
+    QTC_ASSERT(state() == InferiorShutdownRequested, qDebug() << state());
     m_engine->resetLocation();
     m_targetState = DebuggerFinished;
     m_engine->showMessage(_("CALL: SHUTDOWN INFERIOR"));

src/plugins/debugger/debuggerplugin.cpp

@@ -1906,7 +1906,7 @@ void DebuggerPluginPrivate::toggleBreakpoint(const QString &fileName, int lineNu
 
 void DebuggerPluginPrivate::requestMark(ITextEditor *editor, int lineNumber)
 {
-    if (isDebuggable(editor))
+    if (isDebuggable(editor) && editor && editor->file())
         toggleBreakpoint(editor->file()->fileName(), lineNumber);
 }